Highly Efficient Yellow OLED Using Phosphorescent and Fluorescent Dopants

摘要

The efficiencies of an organic light-emitting diode (OLED) using tris- (8 -hydroxy-quinoline) aluminum (Alq3) as host and tetraphenylnapthacene (Rubrene) as yellow dopant were greatly increased by adding a small amount (0.3 wt% ) of a phosphorescent Ir compound ridium(Ⅲ)bis(3-(2-benzothiazolyl)-7-(diethylamino)-2H-1-benzopyran-2-onato-Nr, C4) (acetyl acetonate) (Ir(C6)2(acac)) sensitizer. The device had a simple structure of indium tin oxide (ITO)/4, 4', 4"tris(N-(2-naphthyl)-N-phenyl-amino) triphenylamine (T-NATA) (40 nm)/N, N'-bis (1-naphthyl)-N, N'-diphenyl-1, 1'-biphenyl-4, 4'-diamine (NPB) (40 nm)/Alq3: Rubrene(0.7 wt% ): Ir(C6)2(acac) (0.3 wt%) (40 nm)/Alq3 (40 nm)/ LiF (1 nm)/ Al (120 nm), and the current efficiencies of this device keep a high value of 13.9 cd/A, even the luminance rising to 37 000 cd/m2. The Commission International d'Eclairage (CIE) coordinates x and y are 0.46, 0. 44 of yellow color. The high efficiency at the high luminance was proposed due to the phosphorescent Ir(C6)2(acac) can harvest the singlet and triplet excitons formed in Alq3 and then efficiently transfer to yellow dopant Rubrene.